holy christ is this a pump or cramping?

Wow been doing fina at about 100mg a day for a little over a week now and I am doing leg extensions and after the 4th set I walked around and my legs almost locked up, it felt like they just cramped I am gettting about 2 gallons of water a day, now is it cramping or just some serious mother fuckin pump because I almost have to stop it is pumped so much and cannot even bend down for about 5 minutes then it goes away?

that happened to my hamstrings doing squats at high reps-wtf
i blamed it on lowering my juice intake to low and not recovering from the earlier martial arts session. but that was it for legs after one set felt like they were splitting